Dermatology

Question 1

What is Steven’s Johnson syndrome

Answer 1

Severe form of erythema multiforme and a variant of toxic epidermal necrolysis

Question 2

Name 6 drug causes Steven’s Johnson

Answer 2

• Sulphonamides (bactrim)
• NNRTI: efavirenz, nevirapine
• penicillin
• barbiturates (CNS depressant eg phenobarbital)
• salicylates
• carbamazepine, phenytoin

Question 3

What is toxic epidermal necrolysis

Answer 3

Blistering > 30% of skin surface area

Question 4

Erythema nodosum vs multiforme vs marginatum is infectiosum?

Answer 4

• Nodosum: painful subcutaneous nodules on shins. One of causes is IBD.
• multiforme: dusky, targetOid rash after infection / drug
• marginatum: rheumatic fever
• erythema infectiosum: parvovirus b 19 - slapped cheek

Question 5

Erythema multiforme vs Steven’s Johnsons vs TEN? (5)

Answer 5

• < 10% TBSA vs 10 - 30 vs > 30%
• hands / forearms / oral vs 2 or more mucosal sites vs everywhere
• target lesions vs - vs peeling: positive Nikolsky’s sign
• • vs more common in children vs elderly
• • vs URI prodrome vs abrupt onset

Question 6

Define macule

Answer 6

Circumscribed flat area of colour change 1 cm or less in diameter
Patch >1cm

Question 7

Define papule

Answer 7

Discrete elevation 1 cm or less

Question 8

Define nodule

Answer 8

Like papule but deeper into dermis/ subcutaneous layer, > 1cm

Question 9

Define plaque

Answer 9

Raised area > 1 cm diameter with flat top

Question 10

Define petechia / purpura

Answer 10

Petechia = tiny macules due to extravascular blood in dermis
purpura = larger, may be palpable

Question 11

Name 5 features malignant melanoma

Answer 11

ABCDE

• asymmetry
• border irregular
• colour irregular
• Diameter > 0,5 cm
• elevation irregular
  Loss of skin markings

Question 12

Name 8 causes scaly rashes

Answer 12

• Atopic eczema: face+flexures, shiny nails, “dirty neck “, infra-orbital crease
• psoriasis: extensor surfaces + lower back , nail pitting/ onycholysis, kobner phenomenon
• pityriasis rosea: ‘ fir tree” pattern on trunk, herald patch, well defined
• drug eruption
• pityriasis versicolor: upper trunk + shoulders
• lichen planus: distal limbs + flexural aspect wrists + lower back, white lacy network on buccal mucosa
• tinea corporis: asymmetrical isolated lesions
• secondary syphilis: trunk + proximal limbs + palms+ soles, history chancre

Question 13

Name 5 causes vesicular rash

Answer 13

Localised:

• HSV
• HZV
• impetigo
• pompholyx / dyshidrotic eczema

Generalised:

• Eczema herpeticum (mucosal involvement)
• dermatitis herpetiformis
• acute eczema

Question 14

Name 5 causes bullOus rash

Answer 14

Localised

• impetigo
• cellulitis
• stasis oedema
• acute eczema
• insect bite
• fixed drug eruption

Generalised

• ten (mucosal involvement)
• erythema multiforme
• Steven’s Johnson syndrome (mucosal involvement)
• lupus erythematosus
• porphyria cutanea tarda
• bullous pemphigoid
• pemphigus (mucosal involvement)
• epidermolysis bullOsa acquisita
• pseudo porphyria

Question 15

Main differential for toxic epidermal necrolysis?

Answer 15

Staphylococcal scalded skin syndrome

Question 16

Describe the Disease severity score for toxic epidermal necrolysis (SCORTEN) (7)

Answer 16

• Age > 40
• HR > 120
• cancer / haematological malignancy
• involved body surface area > 10%
• blood urea > 10 mmo/ l
• serum bicarb < 20 mmol/l
• glucose 14 or more mmol/l

Mortality rate:
0-1 factors = 3%
2=12%
3=35%
4=58%
5 or more: 90%

Question 17

Name 2 other organs involved in ten

Answer 17

Ocular and urethral scarring